The present invention is directed to a bi-directional seal assembly for sealing the annulus between an inner tubular member and an outer tubular member. In particular, the invention is directed to a seal assembly which includes an annular metal seal that in cross section comprises two generally U-shaped portions which enable the seal to be pressure energized from both above and below the seal assembly. The seal can be installed as an interference fit between the tubular members or mechanically energized into sealing engagement with the tubular members after it is installed.
Packoffs are commonly used in hydrocarbon production wells to seal the annulus between a wellhead and, e.g., a casing hanger which is landed in the wellhead. These prior art packoffs often include one or more metal seals which are supported on a packoff body that is locked in place between the casing hanger and the wellhead. Either during or after installation of the packoff, the seals are either mechanically or pressure energized into sealing engagement with both the wellhead and the casing hanger.
Many prior art packoffs have only one metal seal and are uni-directional, that is, they are designed to seal in only one direction. This poses difficulties when it is desired to pressure test the packoff from a port external to the wellhead. Some packoffs include elastomer seals for purposes of pressure testing. However, over time the elastomer can fail and the ability to test the packoff is consequently lost.
Therefore, a need exists for a packoff seal which is bi-directional, that is, which is capable of sealing from both above and below. In addition, a need exists for a bi-directional packoff seal whose pressure reliability in both directions can be proved by pressure testing the packoff from only one direction.